I passed CFA Level 1 before entering the bschool and here are my impressions regarding the CFA designation:
1) It impresses your potential recruiters and fellow students more than the admissions office or any professors. Remember, adcom/professors, etc are academics. They are more impressed with other things on your app, than your CFA credential.
2) It's also not as impressive to the recruiters unless you have relevant experience (internship, other work exp, etc) on your resume. CFA by itself simply demonstrates "how serious you are about pursuing a career in financial services" and your level of interest in the field.
It's not a make or break factor for admissions, but pretty important once you get a job. So, I would concentrate on getting into a program NOW, and then worry about it later.